Inter-stage seal for a turbomachine

ABSTRACT

An inter-stage seal for a turbomachine includes a sealing member extending from a first end to a second end through an intermediate portion having a sealing surface, a first mounting member extending from a first end portion coupled to the sealing member adjacent the first end to a second, cantilevered end portion having a first rotor mounting element, and a second mounting member extending from a first end portion coupled to the sealing member adjacent the second end to a second, cantilevered end portion having a second rotor mounting element.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to the art of turbomachines and, more particularly, to an inter-stage seal for a turbine portion of a turbomachine.

Turbomachines include a compressor portion linked to a turbine portion through a common compressor/turbine shaft and a combustor assembly. An inlet airflow is passed through an air intake toward the compressor portion. In the compressor portion, the inlet airflow is compressed through a number of sequential stages toward the combustor assembly. In the combustor assembly, the compressed airflow mixes with a fuel to form a combustible mixture. The combustible mixture is combusted in the combustor assembly to form hot gases. The hot gases are guided along a hot gas path of the turbine portion through a transition piece. The hot gases expand through a number of turbine stages acting upon turbine buckets mounted on wheels to create work that is output, for example, to power a generator, a pump, or to provide power to a vehicle. Exhaust gases from the turbine portion are often times passed to a heat recovery steam generator which creates a steam flow that is passed to a steam turbine portion.

Additional gases, in the form of compressor air, may pass into the turbine portion, or in the form of lower temperature air, may enter wheel spaces in turbine portion to cool a rotor and/or a wheel. In a steam turbine, lower temperature steam may be fed into wheel spaces of early stages to cool the rotor that supports rotating buckets. In either case, inter-stage seals substantially isolate the hot gases, or working fluids, flowing along the hot gas path and the fluids used for cooling purposes. The inter-stage seals typically include axial outwardly extending arms that cooperate with turbine blade angel wings to reduce leakage. Typical angel wing seals involve a rotating seal tooth or sealing face mating with a stationary counterpart. There typically exists a clearance between a rotating component and a stationary component to reduce contact or rubbing. The clearance may allow leakage to flow between the rotating component and the stationary component. The leakage flow may increase cooling requirements that may negatively impact turbomachine efficiency. Reducing working fluid leakage increases turbomachine efficiency.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the exemplary embodiment, an inter-stage seal for a turbomachine includes a sealing member extending from a first end to a second end through an intermediate portion having a sealing surface, a first mounting member extending from a first end portion coupled to the sealing member adjacent the first end to a second, cantilevered end portion having a first rotor mounting element, and a second mounting member extending from a first end portion coupled to the sealing member adjacent the second end to a second, cantilevered end portion having a second rotor mounting element.

According to another aspect of the exemplary embodiment, a turbomachine includes a turbine portion having a first stage rotor supporting a plurality of first stage turbine blades and a second stage rotor supporting a plurality of second stage turbine blades. At least one inter-stage seal extends between the first and second stage rotors. The at least one inter-stage seal includes a sealing member extending from a first end to a second end through an intermediate portion having a sealing surface, a first mounting member extending from a first end portion coupled to the sealing member adjacent the first end to a second, cantilevered end portion having a first rotor mounting element connected to the first stage rotor, and a second mounting member extending from a first end portion coupled to the sealing member adjacent the second end to a second, cantilevered end portion having a second rotor mounting element connected to the second stage rotor.

According to yet another aspect of the exemplary embodiment, a method of sealing between adjacent stages in a turbomachine includes positioning an inter-stage seal across a rotor, axially shifting the inter-stage seal across the rotor, arranging a sealing member of the inter-stage seal across a gap extending between the rotor and an adjacent rotor, connecting a first mounting member extending from a first end of the sealing member with the rotor, and connecting a second mounting member extending from a second end of the sealing member to the another rotor.

These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF DRAWINGS

The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a cross-sectional side view of a turbomachine including an inter-stage seal, in accordance with an exemplary embodiment;

FIG. 2 is a partial plan view of a turbine portion of the turbomachine of FIG. 1;

FIG. 3 is a perspective view of the inter-stage seal of FIG. 1;

FIG. 4 is a plan view of an inter-stage seal being positioned across a rotor of the turbomachine of FIG. 1;

FIG. 5 is a plan view of the inter-stage seal straddling the rotor of FIG. 4;

FIG. 6 is a plan view of the inter-stage seal axially shifting toward another rotor of the turbomachine; and

FIG. 7 is a plan view of the inter-stage seal connected to the rotor and the another rotor, in accordance with an exemplary embodiment.

The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.

DETAILED DESCRIPTION OF THE INVENTION

A turbomachine, in accordance with an exemplary embodiment, is indicated generally at 2, in FIG. 1. Turbomachine 2 takes the form of a turbine portion 4 having a housing 5 that surrounds a plurality of turbine stages 6. Turbine stages 6 include a first stage 8. First stage 8 includes a plurality of first stage vanes or nozzles, one of which is indicated at 10, and a plurality of first stage axial entry buckets or blades, one of which is indicated at 12. Blades 12 are mounted to a first stage rotor 14 through a plurality of dovetail slots 15. First stage rotor 14 includes one or more axial locking members 16 that constrain axial movement of blades 12.

Plurality of turbine stages 6 also include a second stage 18 arranged downstream of first stage 8. Second stage 18 includes a plurality of second stage vanes or nozzles, one of which is indicated at 20, and a plurality of second stage axial entry buckets or blades, one of which is indicated at 22. Blades 22 are mounted to a second stage rotor 24 through a plurality of dovetail slots 25. Second stage rotor 20 includes one or more axial locking members 26 that constrain axial movement of blades 22. A third stage 28 is arranged downstream of second stage 18. Third stage 28 includes a plurality of third stage vanes or nozzles, one of which is indicated at 30, and a plurality of third stage axial entry buckets or blades, one of which is indicated at 32. Blades 32 are mounted to a third stage rotor 34 through a plurality of dovetail slots 35. Third stage rotor 34 includes one or more axial locking members 36 that constrain axial movement of blades 32. Blades 12, 22, and 32 extend along a hot gas path 37 of turbine portion 8.

A working fluid, in the form of hot gases that may include products of combustion or steam, expands through turbine stages 6 to an outlet (not separately labeled) acting upon the first, second, and third stage blades 12, 22, and 32. The force of the hot gases impacting the first, second, and third stage blades 12, 22 and 32 is transmitted to first, second, and third stage rotors 14, 24 and 34 which rotate. Rotational energy from the first, second, and third stage rotors 14, 24, and 34 is transmitted to a load (not shown) through a shaft (not separately labeled). In addition to the working fluid, a cooling fluid is passed through a wheelspace portion 38 of turbine portion 4. Wheelspace portion 38 may include inter-rotor spaces between adjacent rotors 14, 24 and 24, 34 such as shown at 38 a and 38 b respectively. Wheelspace portion 38 may also include a portion 39 that exists between stationary components (not separately labeled) and rotor 14.

In order to limit hot gas ingestion into spaces 38 a and 38 b and other inter-wheel spaces (not shown), and to reduce leakage of the cooling fluid, turbine portion 4 includes a first inter-stage seal 40 arranged between first and second rotors 14 and 24 in stages 8 and 18 respectively, and a second inter-stage seal 44 arranged between rotors 24 and 44 in second and third stages 18 and 28, respectively. In accordance with an aspect of the invention, a conventional angel wing seal (not shown) may be placed on an upstream side (not separately labeled) of first stage rotor 14. Of course it should be understood that other types of seals, including an inter-stage seal 40 could be used. At this point it should be understood that the number of stages and inter-stage seals may vary.

Reference will now be made to FIGS. 2-3 in describing first inter-stage seal 40, in accordance with an exemplary embodiment, with an understanding that second inter-stage seal 44 may include similar structure. First inter-stage seal 40 includes a sealing member 60 that extends from a first end 62 to a second end 63 through an intermediate portion 65. Intermediate portion 65 includes a sealing surface 67 and an opposing, cooling surface 69. Sealing surface 67 includes one or more radially outwardly projecting sealing elements 72. When installed, sealing elements 72 extend toward a bottom surface of, for example, second stage nozzles 20.

Inter-stage seal 40 also includes a first mounting member 81 that interfaces with first stage rotor 14 and a second mounting member 84 that interfaces with second stage rotor 24, as will be detailed more fully below. First mounting member 81 extends from a first end portion 90 to a second, cantilevered, end portion 91. First end portion 90 extends from first end 62 and second end portion 91 includes a first rotor mounting element 94. First rotor mounting element 94 takes the form of a dovetail member 96 that is configured to slidingly engage with dovetail slot 15. Second mounting member 84 extends from a first end portion 104 to a second, cantilevered, end portion 105. First end portion 104 extends from second end 63 and second end portion 105 includes a second rotor mounting element 108. Second rotor mounting element 108 takes the form of a dovetail member 110 that is configured to slidingly engage with dovetail slot 25. In the exemplary embodiment, first and second rotor mounting elements 94 and 108 are shown as complete dovetails. It should be readily understood that first and second rotor mounting elements 94 and 108 can also take the form of partial or whole form dovetails having various geometries that structurally match dovetail slots on the rotor. First and second ends 62 and 63 abut, or nearly abut, base portions (not separately labeled) of corresponding ones of first stage blades 12 and second stage blades 22. In accordance with an aspect of the exemplary embodiment, inter-stage seal 40 rotates together with first and second stage blades 12 and 22. Accordingly, gaps between abutting surfaces may be set to very small dimensions that effectively fluidically separate inter-rotor spaces 38 a and 38 b from hot gas path 37.

Reference will now be made to FIGS. 4-7 in describing a method of installing inter-stage seal 40, in accordance with an aspect of the exemplary embodiment. As shown in FIG. 4, inter-stage seal 40 is positioned at first stage rotor 14 prior to the installation of first stage blades 12. Inter-stage seal 40 is moved into position such that first and second mounting members 81 and 84 straddle first stage rotor 14, as shown in FIG. 5. Inter-stage seal 40 is axially shifted causing dovetail member 96 to pass into dovetail slot 15, as shown in FIG. 6. Inter-stage seal 40 is further axially shifted until dovetail member 110 enters dovetail slot 25 in second rotor 24, as shown in FIG. 7. At this point, additional inter-stage seals may be mounted to first stage rotor 14, or first stage rotor blades 12 may be installed and locked into position. In the exemplary embodiment, each rotor wheel may include balance holes 120, 122, and 124 formed in first, second, and third stage rotors 14, 24, and 34. Balance holes 120, 122, and 124may pass cooling flow between inter-rotor spaces 38 a and 38 b and the like.

At this point it should be understood that the exemplary embodiments describe an inter-stage seal for a turbine. The inter-stage seal joins adjacent rotors doing away with the need for turbine wheels and corresponding seals. The particular shape of the inter-stage seal also removes the need for angel wings provided on the rotor blades for sealing purposes. The inter-stage seal, in accordance with the exemplary embodiment, contributes to an overall reduction in axial length of a turbine while maintaining a desired separation between working fluid and cooling fluid flows. At this point it should be understood that the inter-stage seal, in accordance with exemplary embodiment, may be employed in a gas turbine or a steam turbine. It should be further understood that the particular geometry of the inter-stage seal may vary and should not be limited to the geometries shown.

While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims. 

What is claimed is:
 1. An inter-stage seal for a turbomachine comprising: a sealing member extending from a first end to a second end through an intermediate portion having a sealing surface; a first mounting member extending from a first end portion coupled to the sealing member adjacent the first end to a second, cantilevered end portion having a first rotor mounting element; and a second mounting member extending from a first end portion coupled to the sealing member adjacent the second end to a second, cantilevered end portion having a second rotor mounting element.
 2. The inter-stage seal according to claim 1, further comprising: a plurality of sealing elements extending outwardly from the sealing surface.
 3. The inter-stage seal according to claim 1, wherein the first end is cantilevered from the first mounting member.
 4. The inter-stage seal according to claim 1, wherein the second end is cantilevered from the second mounting member.
 5. The inter-stage seal according to claim 1, wherein each of the first and second rotor mounting elements comprise dovetail members.
 6. A turbomachine comprising: a first stage rotor supporting a plurality of first stage turbine blades and a second stage rotor supporting a plurality of second stage turbine blades; at least one inter-stage seal extending between the first and second stage rotors, the at least one inter-stage seal comprising: a sealing member extending from a first end to a second end through an intermediate portion having a sealing surface; a first mounting member extending from a first end portion coupled to the sealing member adjacent the first end to a second, cantilevered end portion having a first rotor mounting element connected to the first stage rotor; and a second mounting member extending from a first end portion coupled to the sealing member adjacent the second end to a second, cantilevered end portion having a second rotor mounting element connected to the second stage rotor.
 7. The turbomachine according to claim 6, further comprising: a plurality of sealing elements extending outwardly from the sealing surface.
 8. The turbomachine according to claim 7, wherein the at least one inter-stage seal is arranged in a turbine portion of the turbomachine, the plurality of sealing elements extending toward a nozzle.
 9. The turbomachine according to claim 6, wherein the first end is cantilevered from the first mounting member.
 10. The turbomachine according to claim 6, wherein the second end is cantilevered from the second mounting member.
 11. The turbomachine according to claim 6, wherein each of the first and second rotor mounting elements comprise dovetail members.
 12. The turbomachine according to claim 6, further comprising: at least one axial locking member provided on one of the first and second stage rotors, the at least one axial locking member constraining axial movement of one or more of the first and second stage blades.
 13. A method of sealing between adjacent stages in a turbomachine, the method comprising: positioning an inter-stage seal across a rotor; axially shifting the inter-stage seal across the rotor; arranging a sealing member of the inter-stage seal across a gap extending between the rotor and an adjacent rotor; connecting a first mounting member extending from a first end of the sealing member with the rotor; and connecting a second mounting member extending from a second end of the sealing member to the adjacent rotor.
 14. The method of claim 13, wherein connecting the first mounting member to the rotor includes sliding a dovetail member provided on the first mounting member into a dovetail slot formed in the rotor.
 15. The method of claim 14, further comprising: installing an axial entry blade member into the dovetail slot formed in the rotor.
 16. The method of claim 15, further comprising: installing an axial locking member to the rotor to constrain axial movement of the blade member.
 17. The method of claim 14, wherein connecting the second mounting member to the adjacent rotor includes sliding a dovetail member provided on the second mounting member into a dovetail slot formed in the adjacent rotor.
 18. The method of claim 13, further comprising: abutting a portion of the sealing member with a blade member provided in the adjacent rotor.
 19. The method of claim 13, wherein positioning the inter-stage seal across the rotor includes straddling the rotor with the first and second mounting members extending axially inwardly on opposing sides of the rotor.
 20. The method of claim 13, wherein positioning the inter-stage seal across the rotor includes positioning the inter-stage seal in a turbine portion of the turbomachine. 